Development and Mechanical Performance of Self-Compacting Lightweight Aggregate Concrete Using Sintered Fly Ash Aggregates

Abstract

The creation of lightweight aggregate self-compacting concrete (LWA-SCC) is a challenging endeavor with substantial consequences for the construction sector. However, the absence of firmly established design suggestions and recommendations as well as the limited availability of design approaches pose a noteworthy obstacle. To accomplish the anticipated mechanical properties while minimizing production costs as well as preserving natural resources, a thorough comprehension and understanding of the optimal combination of binders and coarse aggregate content is required. This study examines the impact of several supplementary cementitious materials (SCMs) such as silica fume (SF) and metakaolin (MK) on the fundamental mechanical characteristics of ecofriendly LWA-SCC mixes prepared with 100% sintered fly ash aggregate (SFAA) as a replacement of natural coarse aggregates (NCAs). A total of nine LWA-SCC mixes were prepared including one base SCC mix. The base SCC mix (C-SFAA100) encompasses 100% ordinary portland cement (OPC) as the sole binder, and 100% natural fine aggregates (NFAs) along with 100% SFAA. The remaining eight mixes were further parted into two Series. Series I and Series II comprise SF and MK as a replacement for OPC by 7.5%, 10%, 12.5%, and 15%, respectively. The fundamental mechanical characteristics such as compressive strength, split tensile strength, direct shear, and elastic modulus were measured after several intervals. In addition, microstructural analyses were also executed to appraise the overall efficacy of LWA-SCC combinations. The results such as the compressive strength of the SCC mixes CSF15-SFAA100 and CMK15-SFAA100 increased by 11.3% and 18.5%, respectively, after a curing time of 90 days compared to the base SCC mix C-SFAA100 confirmed that the incorporation of SCMs into LWA-SCC mixtures improves their mechanical characteristics.